1. Technical Field
The present invention relates to optical sensors in general, and in particular to a method for fabricating infrared sensors.
2. Description of Related Art
A bolometer type infrared sensor is an optical sensor that detects infrared radiation by using a material capable of changing resistance values based on temperatures. In conjunction with an absorber for converting electromagnetic radiation to heat, and a detector for measuring an increase in temperature, a bolometer can measure the intensity of electromagnetic radiation of a specific wavelength range (such as 3-15 μm). Depending on a thermal capacity of the material, there is a direct connection between the amount of radiation absorbed and the resulting increase in temperature. Thus, the increase in temperature may serve as a measure of the intensity of an incident radiation.
A bolometer may be used as an infrared sensor, an imager for a night-vision device or as a thermal imaging camera. A bolometer serving as an infrared sensor includes a thin layer that is arranged within the sensor in a thermally insulated manner, e.g., suspended as a membrane. The infrared radiation is absorbed within the membrane whose temperature increases as a result. If the membrane includes a metallic or a semiconducting material, the electrical resistance will change depending on the increase in temperature and on the temperature coefficient of resistance of the material being used. Alternatively, the membrane can be an insulator (such as an oxide) onto which the resistor has been deposited as a further thin layer.
The present disclosure provides a method for fabricating optical sensors such as bolmeters.